In recent years there has been a tremendous worldwide effort to develop motor vehicles operated by a fuel other than a petroleum distillate. Such efforts have resulted in hydrogen powered vehicles, steam powered vehicles and electric powered vehicles, the latter of which has been adopted as the most promising alternative to the normal gasoline consuming internal combustion engine. With the adoption of the electric motor vehicle, as the proposed answer to such a crucial problem, there has been a need to develop an on-board source of electrical power. Since fuel cells, nuclear generators and other systems have not been perfected to a degree which allows their immediate use on motor vehicles, most developmental efforts in commercializing electric powered motor vehicles now involve the use of a storage battery carried by the vehicle. For that reason, various types of storage batteries have been developed with the objective of increasing the range between charging, without sacrificing operating speed and/or decreasing the time and effort required in actually charging the on-board storage battery. These objectives have now been generally satisfied by a zinc-chloride battery of the type commercialized by Energy Development Associates and disclosed generally in U.S. Pat. No. 3,935,024. This patent is incorporated by reference herein as background information regarding the power supply or main storage battery to which the present invention is particularly applicable.
When employing a zinc-chloride battery, it is desirable to cool an area of the battery during the charging cycle to facilitate the formation of chlorine hydrate. The optimum temperature to which this battery area should be cooled varies as the charged state of the battery increases. Thus, it is necessary to monitor the cooling of the controlled areas of the zinc-chloride battery to optimize the parameters of the charging cycle. This is done to control battery pressures, which pressures are responsive to changes in heat within the controlled area of the zone-chloride battery. This monitored and controlled battery area is generally the area at which a minor amount of electrolyte is pumped or bypassed from the basic battery chamber or stack to the chlorine-hydrate storage area. There is a substantial need for a method and apparatus to control the cooling in this area of the battery, which cooling method can be accurately controlled to optimize the battery charging cycle.